What should I do if I forget a dose?

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take more than one dose of emtricitabine in one day and do not take a double dose to make up for a missed one.

What side effects can this medication cause?

Emtricitabine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

headache

diarrhea

change in skin color, especially on the palms of the hands or the soles of the feet

indigestion

joint pain

unusual dreams

depression

trouble falling asleep or staying asleep

numbness, burning, or tingling in the hands, arms, feet, or legs

runny nose

Some side effects can be serious. If you experience any of the following symptoms, or those mentioned in the IMPORTANT WARNING section, call your doctor immediately:

fever, chills, sore throat, cough, or other signs of infection

rash

Emtricitabine may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

What other information should I know?

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

Clinical pharmacology

Mechanism of Action

Emtricitabine is an antiviral drug.

Pharmacokinetics

Adults

The pharmacokinetics of emtricitabine were evaluated in healthy subjects and HIV-1- infected subjects. Emtricitabine pharmacokinetics are similar between these populations.

The multiple dose pharmacokinetics of emtricitabine are dose proportional over a dose range of 25–200 mg.

Distribution

In vitro binding of emtricitabine to human plasma proteins was less than 4% and independent of concentration over the range of 0.02–200 μg/mL. At peak plasma concentration, the mean plasma to blood drug concentration ratio was ~1.0 and the mean semen to plasma drug concentration ratio was ~4.0.

Metabolism

In vitro studies indicate that emtricitabine is not an inhibitor of human CYP450 enzymes. Following administration of 14C-emtricitabine, complete recovery of the dose was achieved in urine (~86%) and feces (~14%). Thirteen percent (13%) of the dose was recovered in urine as three putative metabolites. The biotransformation of emtricitabine includes oxidation of the thiol moiety to form the 3'-sulfoxide diastereomers (~9% of dose) and conjugation with glucuronic acid to form 2'-O-glucuronide (~4% of dose). No other metabolites were identifiable.

Elimination

The plasma emtricitabine half-life is approximately 10 hours. The renal clearance of emtricitabine is greater than the estimated creatinine clearance, suggesting elimination by both glomerular filtration and active tubular secretion. There may be competition for elimination with other compounds that are also renally eliminated.

Effects of Food on Oral Absorption

EMTRIVA capsules and oral solution may be taken with or without food. Emtricitabine systemic exposure (AUC) was unaffected while Cmax decreased by 29% when EMTRIVA capsules were administered with food (an approximately 1000 kcal high-fat meal). Emtricitabine systemic exposure (AUC) and Cmax were unaffected when 200 mg EMTRIVA oral solution was administered with either a high-fat or low-fat meal.

Special Populations

Race, Gender

The pharmacokinetics of emtricitabine were similar in adult male and female subjects and no pharmacokinetic differences due to race have been identified.

Pediatric Patients

The pharmacokinetics of emtricitabine at steady state were determined in 77 HIV-1-infected pediatric subjects, and the pharmacokinetic profile was characterized in four age groups (Table 6). The emtricitabine exposure achieved in pediatric subjects receiving a daily dose of 6 mg/kg up to a maximum of 240 mg oral solution or a 200 mg capsule is similar to exposures achieved in adult subjects receiving a once-daily dose of 200 mg.

The pharmacokinetics of emtricitabine were studied in 20 neonates born to HIV-1- positive mothers. Each mother received prenatal and intrapartum combination antiretroviral therapy. Neonates received up to 6 weeks of zidovudine prophylactically after birth. The neonates were administered two short courses of emtricitabine oral solution (each 3 mg/kg once daily x 4 days) during the first 3 months of life. The AUC observed in neonates who received a daily dose of 3 mg/kg of emtricitabine was similar to the AUC observed in pediatric subjects ages 3 months to 17 years who received a daily dose of emtricitabine as a 6 mg/kg oral solution up to 240 mg or as a 200 mg capsule (Table 6).

a Two pharmacokinetic evaluations were conducted in 20 neonates over the first 3 months of life. Median (range) age of infant on day of pharmacokinetic evaluation was 26 (5–81) days. b Mean (range)

Geriatric Patients

The pharmacokinetics of emtricitabine have not been fully evaluated in the elderly.

Patients with Impaired Renal Function

The pharmacokinetics of emtricitabine are altered in subjects with renal impairment [See WARNINGS AND PRECAUTIONS]. In adult subjects with creatinine clearance less than 50 mL/min or with end-stage renal disease (ESRD) requiring dialysis, Cmax and AUC of emtricitabine were increased due to a reduction in renal clearance (Table 7). It is recommended that the dosing interval for EMTRIVA be modified in adult patients with creatinine clearance less than 50 mL/min or in adult patients with ESRD who require dialysis [See DOSAGE AND ADMINISTRATION]. The effects of renal impairment on emtricitabine pharmacokinetics in pediatric patients are not known.

Hemodialysis: Hemodialysis treatment removes approximately 30% of the emtricitabine dose over a 3-hour dialysis period starting within 1.5 hours of emtricitabine dosing (blood flow rate of 400 mL/min and a dialysate flow rate of 600 mL/min). It is not known whether emtricitabine can be removed by peritoneal dialysis.

Patients with Hepatic Impairment

The pharmacokinetics of emtricitabine have not been studied in subjects with hepatic impairment, however, emtricitabine is not metabolized by liver enzymes, so the impact of liver impairment should be limited.

Assessment of Drug Interactions

At concentrations up to 14-fold higher than those observed in vivo, emtricitabine did not inhibit in vitro drug metabolism mediated by any of the following human CYP isoforms: CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6, and CYP3A4. Emtricitabine did not inhibit the enzyme responsible for glucuronidation (uridine-5'- disphosphoglucuronyl transferase). Based on the results of these in vitro experiments and the known elimination pathways of emtricitabine, the potential for CYP mediated interactions involving emtricitabine with other medicinal products is low.

EMTRIVA has been evaluated in healthy volunteers in combination with tenofovir disoproxil fumarate (DF), zidovudine, indinavir, famciclovir, and stavudine. Tables 8 and 9 summarize the pharmacokinetic effects of coadministered drug on emtricitabine pharmacokinetics and effects of emtricitabine on the pharmacokinetics of coadministered drug.

Table 8 : Drug Interactions: Change in Pharmacokinetic Parameters for Emtricitabine in the Presence of the Coadministered Druga

Microbiology

Mechanism of Action

Emtricitabine, a synthetic nucleoside analog of cytidine, is phosphorylated by cellular enzymes to form emtricitabine 5'-triphosphate. Emtricitabine 5'-triphosphate inhibits the activity of the HIV-1 reverse transcriptase by competing with the natural substrate deoxycytidine 5'-triphosphate and by being incorporated into nascent viral DNA which results in chain termination. Emtricitabine 5'-triphosphate is a weak inhibitor of mammalian DNA polymerase α, β, ε, and mitochondrial DNA polymerase γ.

The in vivo activity of emtricitabine was evaluated in two clinical trials in which 101 subjects were administered 25–400 mg a day of EMTRIVA as monotherapy for 10– 14 days. A dose-related antiviral effect was observed, with a median decrease from baseline in plasma HIV-1 RNA of 1.3 log10 at a dose of 25 mg once daily and 1.7 log10 to 1.9 log10 at a dose of 200 mg once daily or twice daily.

Resistance

Emtricitabine-resistant isolates of HIV-1 have been selected in cell culture and in vivo. Genotypic analysis of these isolates showed that the reduced susceptibility to emtricitabine was associated with a substitution in the HIV-1 reverse transcriptase gene at codon 184 which resulted in an amino acid substitution of methionine by valine or isoleucine (M184V/I).

Emtricitabine-resistant isolates of HIV-1 have been recovered from some subjects treated with emtricitabine alone or in combination with other antiretroviral agents. In a clinical trial of treatment-naive subjects treated with EMTRIVA, didanosine, and efavirenz [See Clinical Studies], viral isolates from 37.5% of subjects with virologic failure showed reduced susceptibility to emtricitabine. Genotypic analysis of these isolates showed that the resistance was due to M184V/I substitutions in the HIV-1 reverse transcriptase gene.

In a clinical trial of treatment-naive subjects treated with either EMTRIVA, VIREAD, and efavirenz or zidovudine/lamivudine and efavirenz [See Clinical Studies], resistance analysis was performed on HIV-1 isolates from all confirmed virologic failure subjects with greater than 400 copies/mL of HIV-1 RNA at Week 144 or early discontinuation. Development of efavirenz resistance-associated substitutions occurred most frequently and was similar between the treatment arms. The M184V amino acid substitution, associated with resistance to EMTRIVA and lamivudine, was observed in 2/19 analyzed subject isolates in the EMTRIVA + VIREAD group and in 10/29 analyzed subject isolates in the lamivudine/zidovudine group. Through 144 weeks of Study 934, no subjects have developed a detectable K65R substitution in their HIV-1 as analyzed through standard genotypic analysis.

Emtricitabine Overview

Emtricitabine is a prescription medication used to treat human immunodeficiency virus (HIV) infections in adults and children. Emtricitabine belongs to a group of drugs called nucleoside reverse transcriptase inhibitors (NRTI), which decrease the amount of HIV in the blood.

This medication comes in capsule and oral solution (liquid) forms. It is taken once a day, with or without food.

Common side effects include headache, diarrhea, nausea and dizziness.

Emtricitabine Food Interactions

Medicines can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of emtricitabine there are no specific foods that you must exclude from your diet when receiving this medication.

What is the most important information i should know about emtricitabine (emtriva)?

Some people develop lactic acidosis while taking emtricitabine. Early symptoms may get worse over time and this condition can be fatal. Get emergency medical help if you have even mild symptoms such as: muscle pain or weakness, numb or cold feeling in your arms and legs, trouble breathing, stomach pain, nausea with vomiting, fast or uneven heart rate, dizziness, or feeling very weak or tired.

Emtricitabine may also cause severe liver damage, which can be fatal. Call your doctor at once if you have any of these symptoms of liver problems: nausea, stomach pain, low fever, loss of appetite, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).

If you have hepatitis B you may develop liver symptoms after you stop taking this medication, even months after stopping. Your doctor may want to check your liver function for several months after you stop using emtricitabine. Visit your doctor regularly.

Taking this medication will not prevent you from passing HIV to other people. Do not have unprotected sex or share razors or toothbrushes. Talk with your doctor about safe ways to prevent HIV transmission during sex. Sharing drug or medicine needles is never safe, even for a healthy person.

Stability

Storage

Oral

Capsules

Emtricitabine (Emtriva): 25°C (may be exposed to 15–30°C).1

Solution

Emtricitabine (Emtriva): 2–8°C until dispensed.1 For patient use, store at 25°C (may be exposed to 15–30°C); use within 3 months.1

Uses For emtricitabine

Emtricitabine is used in combination with other medicines for the treatment of the infection caused by human immunodeficiency virus (HIV). HIV is the virus that causes acquired immune deficiency syndrome (AIDS).

Emtricitabine will not cure or prevent HIV infection or AIDS. It helps keep HIV from reproducing and appears to slow down the destruction of the immune system. This may help delay problems that are usually related to AIDS or HIV disease from occurring. Emtricitabine will not keep you from spreading HIV to other people. People who receive emtricitabine may continue to have some of the problems usually related to AIDS or HIV disease.

emtricitabine is available only with your doctor's prescription.

Precautions While Using emtricitabine

It is very important that your doctor check your or your child's progress at regular visits to make sure that emtricitabine is working properly. Blood and urine tests may be needed to check for unwanted effects.

Do not use emtricitabine if you or your child are also taking lamivudine, Atripla®, Combivir®, Complera®, Epivir®, Epivir-HBV®, Epzicom®, Odefsey®, Stribild®, Triumeq®, Trizivir®, or Truvada®. Tell your doctor right away if you or your child are using any of these medicines. Do not start using emtricitabine until your doctor tells you to.

Two rare but serious reactions to emtricitabine are lactic acidosis (build up of acid in the blood) and liver toxicity. These are more common if you are female, very overweight (obese), or have been taking anti-HIV medicines for a long time. Call your doctor right away if you or your child have abdominal or stomach discomfort or cramping, dark urine, a decreased appetite, diarrhea, general feeling of discomfort, light-colored stools, muscle cramping or pain, nausea, unusual tiredness or weakness, trouble breathing, vomiting, or yellow eyes or skin.

Do not change your dose or stop taking emtricitabine, even for a short time, without talking to your doctor.

Your immune system may get stronger when you start taking HIV medicines. Tell your doctor right away if you notice any changes in your health. Sometimes the immune system will start to fight infections that were hidden in your body, such as pneumonia, herpes, or tuberculosis. Autoimmune disorders (such as Graves' disease, polymyositis, and Guillain-Barré syndrome) may also occur.

emtricitabine does not decrease the risk of transmitting the HIV infection to others through sexual contact or by contaminated blood. Make sure you understand and practice safe sex, even if your partner also has HIV. Avoid sharing needles with anyone.

Special Populations Children

Exposure is similar to adults. In neonates, the AUC was similar to the AUC observed in children at least 3 months to 17 years of age.

Storage

Oral solution: Store at 2°C to 8°C (36°F to 46°F). Use within 3 months if stored at 25°C (77°F) with excursions permitted to 15°C to 30°C (59°F to 86°F).

ALERT U.S. Boxed Warning

Posttreatment exacerbation of hepatitis B:

Emtricitabine is not approved for the treatment of chronic hepatitis B virus (HBV) infection, and the safety and efficacy of emtricitabine have not been established in patients coinfected with HBV and HIV-1. Severe acute exacerbations of hepatitis B have been reported in patients who have discontinued emtricitabine. Closely monitor hepatic function with clinical and laboratory follow-up for at least several months in patients who are coinfected with HIV-1 and HBV and discontinue emtricitabine. If appropriate, initiation of anti-HBV therapy may be warranted.

Monitoring Parameters

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

For the Consumer

Applies to emtricitabine: oral capsule, oral solution

Along with its needed effects, emtricitabine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking emtricitabine:

Some side effects of emtricitabine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Abdominal or stomach pain

abnormal dreams

darkening or redness of the skin

depression

dizziness

earache

headache

heartburn or indigestion

itching skin

puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue

Dialysis

Comments: -Doses should be given after dialysis sessions when used on dialysis days.

Emtricitabine Breastfeeding Warnings

Samples of breast milk obtained from 5 HIV-1 infected women showed that emtricitabine is secreted in human milk. Breastfeeding infants whose mothers are being treated with emtricitabine may be at risk for developing viral resistance to emtricitabine. Other emtricitabine-associated risks in such infants are unknown.

Emtricitabine is excreted into human milk. The effects in the nursing infant are unknown. The U.S. Public Health Service Centers for Disease Control and Prevention advise HIV-1 infected women not to breast-feed to avoid postnatal transmission of HIV-1 to a child who may not yet be infected. The manufacturer recommends that due to the potential for HIV-1 transmission and the potential for serious adverse reactions in nursing infants, mothers should not breastfeed while taking emtricitabine.

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